Ideal Water Hardness (April, 2025 Update)

Key Takeaways

The ideal water hardness, where water tastes good but won’t ruin your fixtures and appliances, is generally 3.5–7 grains per gallon or 17.1–120 parts per million.

However, the ideal water hardness for each person depends on what level of hardness or softness they can tolerate.

Some people love softened water. Some people hate it.

To find out how hard your water is and if you need a water softener, send a sample to Tap Score.

To skip the science lesson and find a water softener to sort out your hard water problem, see Drinking Water’s list of the best water softeners.

The Ideal Water Hardness

There isn’t a universally perfect level of water hardness. The right level of water hardness for you is how much you can tolerate.

Some people really hate the feeling of water made soft by a water softener, calling it slimy. Others say it tastes bad, largely because the minerals have been removed. Other people are willing to make that trade-off in favor of soft water’s benefits.

That being said, hard water will become a nuisance when hardness-causing minerals exceed a certain level.

These levels are measured in grains per gallon (gpg) when it comes to water softeners (more on that below), but water hardness is generally measured in parts per million (ppm) or milligrams per liter (mg/L), which are interchangeable.

Here’s a scale depicting the general range of water from soft to very hard in ppm or mg/L:

Soft: 0–17 ppm
Slightly hard: 17.1–60 ppm
Moderately hard: 61–120 ppm
Hard: 121–180 ppm
Very hard: 180+ ppm

Here’s the same scale in grains per gallon:

Soft: <1 gpg
Slightly hard: 1–3.5 gpg
Moderately hard: 3.5–7 gpg
Hard: 7–10.5 gpg
Very hard: >10.5

What Is Hard Water?

Hard water is water with high levels of calcium and magnesium. It poses no health risks at all, but it can cause issues around the house:

Mineral buildup in appliances like water heaters and coffeemakers
Failure of heating elements in water-using appliances
Soap scum around showers and sinks
Scale deposits faucets and fixtures
Dry, itchy skin and dry, lifeless hair
Spotty, filmy dishes and glassware
Poorly performing detergents
Mineral buildup in pipes in extreme cases over long periods of time

While moderately hard water might not be as much of a problem for drinking water, it can cause problems with your appliances, especially any that heat water. Heating elements are like magnets to calcium and magnesium and will get coated in calcium and magnesium carbonate scale, causing them to fail.

That same scale can build up on your faucets and around your sinks. This is because while the water evaporates, the minerals don’t. Instead, they become solid particles known as carbonates, which cause the crusty scale you’re seeing on your fixtures.

Soap reacts with calcium and magnesium in a way that reduces its ability to lather, meaning more soap and detergent are needed to get things clean. You’ll also constantly feel like there’s residue left on your skin after washing your hands and bathing.

Testing for Water Hardness

Determining your water hardness depends on whether you’re on city water or well water.

If you’re hooked up to the municipal water system, your local authorities will issue an annual water report and — most of the time — will tell you the water hardness in your area.

If you get your water from a private well, however, you’ll need to have the water tested yourself. Sure, you can look up estimates of well water hardness in your area, but to know exactly what level of water hardness you’re dealing with — essential for determining what kind of water softener you should get — you’ll need to test the water.

There are two ways to do this.

You can buy your own test kit and use it at home. This typically involves dipping your water in a strip and comparing the strip to a color scale that tells you the results. We’ve compiled a list of the best well water testing kits. Just keep in mind that a home test can only give you a general idea of your water quality, not a highly accurate result down to the parts per million.

Another option is to bottle up some of your water and send it to a certified drinking water lab. Accredited laboratories, such as Tap Score, will produce more-accurate results than a home test kit will, and can even tell you what other contaminants you should be treating for.

How to Solve Water Hardness

To improve your water quality, you can invest in a water softener. Water softeners remove calcium and magnesium in your water supply to reduce water hardness and prevent the effects of hard water.

The most common type of water softener uses ion exchange to replace calcium and magnesium ions with sodium ions. These devices are installed near where water enters your home, often a garage or basement. Hard water goes in, and soft water comes out.

Water softeners come in different sizes to accommodate both different levels of hardness and different sized homes. Small homes with moderately hard water will need a smaller water softener with less softening capacity than a large home with very hard water.

Water softener capacity is measured in grains per gallon. The general range for water softener sizes is 32,000 gpg to over 100,000 gpg. You’ll want to make sure you size your water softener correctly. If your water softener is too small for your home, your water pressure can be severely affected. Then again, you don’t want to pay more for a water softener than you need to.

You may come across critiques of water softeners saying they add considerable sodium to your diet, but this is untrue. An extremely small percentage of people with health concerns may want to avoid water softeners, but even for those people, the amount of sodium in softener water is negligible.

However, water softeners waste water, adding cost and an environmental concern, and add sodium to that wasted water. In some cases, this can affect the local ecosystem. To that end, some states and local governments have banned ion exchange water softeners.

Luckily, a new alternative technology, template-assisted crystallization, can neutralize hardness minerals and reduce the effects on your home. The water conditioners do not soften water or remove calcium and magnesium, but they do lessen your hard water’s ability to damage your appliances and fixtures.

If you’re interested in more information about water softener alternatives, check out my review of SpringWell’s FS1 FutureSoft.

Or you can read more about water softener alternatives in general.

Conclusion

There may not be an ideal water hardness, but there is a general range you can aim for. A good rule of thumb is that anything above 7 gpg or 120 mg/L may cause problems around your home, meaning that you’ll start to see scum and scale in your shower and on your dishes, and you’ll feel it on your skin.

You can test the hardness of your water on your own with test kits or send it off to a lab to figure out whether you need a water softener!

Lucky for you, you’re in the right place. At Drinking Water, we consult industry experts, like our on-staff veteran of the EPA, James Layton, to bring you accurate and useful information about water treatment.

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